1. Field of the Invention
This invention relates to improved casting side dam apparatus and more particularly to improved casting side dam apparatus especially adapted for use in twin-belt continuous casting machines, the improved casting machine equipped with such casting side dam apparatus, and improved dam-blocks for the casting side dam apparatus.
2. Description of the Prior Art
Twin-belt casting machines for continuously casting molten metal are known in the prior art, and are referred to as the Hazelett casting machine. A pair of spaced-apart endless flexible casting belts traveling along above and below a mold region define the upper and lower surfaces of a moving mold in such casting machines. The two side surfaces of the moving mold are defined by a pair of spaced-apart, endless flexible side dams which travel along between the casting belts. Each of the side dams are formed by a multiplicity of slotted blocks strung onto a flexible metal strap. Such an apparatus is disclosed in U.S. Pat. No. 3,955,615, with the dam blocks of such casting machine being made of Bronze Corson alloy which has a reported composition of 1.5 to 2.5% nickel, 0.4 to 0.9% silicon, 0.1 to 0.3% iron, 0.1 to 0.5% chromium, balance copper. Use of the casting machine having the Bronze Corson alloy dam blocks forming the side dams for casting copper resulted in the problems arising of the dam blocks prematurely undergoing intergranular cracking and chipping after only a short period of use equivalent to about 1500 tons of copper cast. The intergranular cracking was attributed to the thermal cycling between temperatures of about 300.degree. F. and about 800.degree. F. to which the dam blocks are subjected to in the operation of the casting machine. The prior art dam blocks of the Bronze Corson also failed to retain conductivity above 35% IACS and hardness above 90 Rockwell B after the short period of use equivalent to about 1500 tons of copper cast.
Twin-belt continuous casting machines are also disclosed in U.S. Pat. Nos. 2,904,860; 3,036,348; 3,949,805; 3,937,274; 3,937,270; 3,921,697; 4,002,197; 3,123,874; 3,878,883; 3,167,830; 3,142,873 and 3,864,973.
The following beryllium-copper alloys are in the alloy prior art and obtainable in commerce. They have previously been given by the Copper Development Association, acting on behalf of the Unified Numbering System, the alloy numbers hereafter set forth: Copper Alloy No. C17500: 2.4%-2.7% Co, 0.4%-0.7% Be, 0.10% maximum Fe, total of Be plus Co plus Cu being 99.5% minimum; Copper Alloy No. C17600: 1.4-1.7% Co, 0.25-0.50% Be, 0.9-1.1% Ag, 0.10% maximum Fe, total of Be plus Co plus Ag plus Cu being 99.5% minimum; Copper Alloy No. C17700: 2.4-2.7% Co, 0.40-0.7% Be, 0.40-0.6% Te, 0.10% Fe maximum, total of Be plus Co plus Te plus Cu being 99.5% minimum; Copper Alloy No. C17000: 1.60-1.79% Be, total of Be plus Cu being 99.5% minimum; Copper Alloy No. C17200: 1.80-2.00% Be, total of Be plus Cu being 99.5% minimum; and Copper Alloy No. C17300: 1.80-2.00% Be, 0.20- 0.6% Pb, total of Be plus Pb plus Cu being 99.5% minimum.